code: def test_main_pool():
      strategy = MainPool()
      assert (
          strategy.get_allocated_address(config, dict())
          == "127.0.0.1:1111"
      )
  
file_path: mars/mars/oscar/backends/mars/tests/test_allocate_strategy.py
imports: import pytest
  from ....None import create_actor_ref
  from ....errors import NoIdleSlot
  from ...allocate_strategy import AddressSpecified, MainPool, RandomSubPool, Random, RandomLabel, IdleLabel
  from ...config import ActorPoolConfig
label_desc: Use image node_id 2 for calling a global function with example usage: test_main_pool() without return types